Scaling and Color space conversion

Equivalent to glupload ! gldownload.

Examples

gst-launch -v videotestsrc ! "video/x-raw-yuv" ! glcolorscale ! ximagesink

gst-launch -v videotestsrc ! "video/x-raw-yuv, width=640, height=480, format=(fourcc)AYUV" ! glcolorscale ! \
  "video/x-raw-yuv, width=320, height=240, format=(fourcc)YV12" ! autovideosink

struct GstGLColorscale

struct GstGLColorscale {
    GstBaseTransform base_transform;

    GstPad *srcpad;
    GstPad *sinkpad;

    GstGLDisplay *display;

    GstVideoFormat input_video_format;
    gint input_video_width;
    gint input_video_height;

    GstVideoFormat output_video_format;
    gint output_video_width;
    gint output_video_height;  
};